Black screen on launch

Hi, I've tried all sorts of solution. From the basics of restarting steam and my computer to deleting everything that has to do with the Walking Dead before re-installing it. Either way I just get a black screen when the game launches. Just black - nothing, and I have to CMD+alt+escape my way out. The game worked throughout episode 1-3. Was in the middle of episode 4 it suddenly would not start up again.

The savegame folder is still there. It is possible that something in there is broken.You can test that by renaming/moving the TheWalkingDead folder from/Users/mariusdalseg/Library/Application Support/Telltale Games/TheWalkingDead

Still doesn't work, but there pops up a new folder with a new preps.prof file everytime I try to open the game. The new Walking Dead folder (application support/telltalegames/walkingdead) also contains a SyncFs folder with three empty folders within it (see attached screenshots).

I just tried installing the game directly on my external hard drive, but with no luck. I've also disabled the Steam Cloud Synchronisation to make sure it doesn't download files that might have been corrupted earlier.